P0541

P0541-LOW VOLTAGE ON THE #1 INTAKE AIR HEATER RELAY

P0541 - Low Voltage On The #1 Intake Air Heater Relay:

WHEN MONITORED
When the ignition is on.

SET CONDITION
When the signal from the #1 intake air heater output does not match the signal from the #1 intake air heater feedback.

POSSIBLE CAUSES
- Loose connection
- Intake air heater relay
- Signal circuit open from relay to ECM
- Signal circuit shorted to battery negative
- ECM
- Intermittent condition

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. RELAY CLICKING
Ignition on, engine not running.
With the scan tool, actuate the #1 Intake Air Heater.

Q: Can you hear the Relay clicking?

YES: Go To 2
NO: Go To 3

2. LOOSE CONNECTION
While the relay is clicking , wiggle the wiring harness and connectors.

Q: Does this interrupt the clicking?

YES: Repair the poor connection. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 3

3. INTAKE AIR HEATER RELAY
Turn the ignition off.
Remove the Intake Air Heater #1 Relay.
Check connectors - Clean/repair as necessary.
Measure the resistance between the signal and return posts of the intake air heater relay.

Q: Is the resistance between 15 and 25 Ohms?

YES: Go To 4
NO: Replace the Intake Air Heater #1 relay. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

4. SIGNAL CIRCUIT OPEN FROM RELAY TO ECM
Disconnect the ECM harness connectors.
Check connectors - Clean/repair as necessary.
Measure the resistance of the intake air heater relay signal circuit between the ECM connector and the intake air heater relay connector.

Q: Is the resistance less than 10 Ohms?

YES: Go To 5
NO: Repair the open signal circuit from PDC to ECM harness connector. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

5. SIGNAL CIRCUIT SHORTED TO BATTERY NEGATIVE
Measure the voltage between the signal circuit of the intake air heater relay and battery negative.

Q: Is the voltage greater than 1 volts?

YES: Repair the signal circuit shorted to Battery negative. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 6

6. ECM
Reconnect the ECM harness connectors.
Disconnect the intake air heater relay signal wire and use a jumper to connect it to battery negative.
Turn the ignition on.
With the scan tool, read DTCs.

Q: Did DTC P0542 set?

YES: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).
NO: Replace the ECM. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1